WEST PALM BEACH — A doctor accused of killing a hotel manager at an all-night cocaine party last year seemed ''very slow mentally'' after a 1983 suicide attempt, colleagues testified Monday.

John Freund, a Palm Beach cancer specialist, has pleaded not guilty by reason of insanity to first-degree murder charges in the July 24, 1984, stabbing of hotel manager Ralph Lee Walker.

Defense lawyers say Freund suffered brain damage when he tried to kill himself with an overdose of morphine in 1983 and was insane during the slaying.

''He seemed to be very slow mentally,'' said Dr. Alexander Miranda. ''He seemed to be very forgetful. He seemed to be a different person entirely.''

Assistant State Attorney Jorge LaBarga, however, said Freund could think clearly and was sane when Walker was killed.

Defense lawyers say the night of the slaying Freund was controlled by co- defendant John Trent, who pleaded guilty to second-degree murder last month. They say Trent could manipulate Freund because of the brain damage.

Doctors who knew the cancer specialist testified in Palm Beach Circuit Court that Freund had a reputation as an excellent, hard-working physician but seemed greatly changed after the suicide attempt.

Doctors told jurors that Freund's privileges at St. Mary's Hospital and Good Samaritan Hospital were revoked.

Dr. Augustin Schwartz said the West Palm Beach hospitals wanted a doctor to oversee Freund's work.

''I didn't think he was capable of handling the intellectual functioning, the decision making, the judgment involved in that kind of practice cancer treatment,'' Schwartz said.

Doctors testified that Freund struggled to regain medical privileges at the hospitals and to continue treating cancer patients.

The night of the slaying, Freund was called to Trent's apartment to subdue Walker, who had become unruly and was demanding sex from a 16-year-old girl, according to court records.

Freund injected Walker with sedatives. Witnesses have said that they later saw Freund with his shirt splattered with blood.

Defense lawyers said they plan to call psychiatrists to testify about Freund's mental state.